(a) Field of the Invention
The present invention relates to an accelerating and supplementing mechanism for use in a fuel feed system and particularly to an accelerating and supplementing mechanism for use in a fuel feed system of the type which continuously measures fuel and concentratedly injects it at a positive pressure into a suction pipe.
(b) Description of the Prior Art
There is known a fuel system of a continuous measuring and concentrated injecting type which, as shown in FIG. 1, comprises a fuel measuring mechanism A comprising a tapered hole 2 arranged in a main body 1, a valve 3 axially slidably installed in the hole 2 and a pressure control unit 4 for maintaining the pressure difference across the valve 3 at a predetermined value, and a flow rate measuring mechanism B which maintains, at a predetermined value, the pressure difference P.sub.1 -P.sub.2 across a flow rate detecting valve 6 disposed in a suction pipe by means of a servo-mechanism (not shown) and measures the amount of air being sucked on the basis of degree of opening of the flow detecting valve 6, wherein unique correspondence between the degree of opening of the flow rate detecting valve 6 and the axial position of the valve 3 is established by a control rod 7.
The feed fuel system of the type described above is arranged so that when the accelerator pedal is operated, the pressure P.sub.2 downstream of the flow rate detecting valve 6 is varied and therefore the flow rate detecting valve 6 is displaced until the pressure difference P.sub.1 -P.sub.2 assumes a predetermined value. This displacement is transferred to the valve 3 by the control rod 7 to vary the axial position of the valve 3 so that the clearance defined between the valve 3 and the hole 2 varies in size.
The pressure difference across the valve 3 is maintained at a constant value by the pressure control unit 4 and the fuel flows through the clearance at a fixed speed and is injected into the suction pipe 5 by a nozzle 9 disposed upstream of a throttle valve 8 on the primary side. In addition, 10 designates a venturi for assisting in the atomization of fuel injected and 11 designates a bypass which connects the venturi to the upstream side of the flow rate detecting valve 6.
With the system shown in FIG. 1, however, it is impossible to increase the follow-up characteristic of quick acceleration to the required degree, thus giving the driver an impression that the accelerating ability is poor.